Low obstruction air conditioners of that type, which straddle the windowsill, allow a lower sash of the window to closely approach the windowsill and thereby do not materially obstruct the view through the window or light and air from the window. The low obstruction window air conditioner has an advantage over units which occupy the bulk of the opening for the lower sash in that the window remains usable.
In U.S. Pat. 5,167,131, for example, such a low obstruction air conditioner is described in which the outer unit contains the compressor, condenser coil and fan while the inner unit contains the evaporator and the air circulator and the inner and outer units are connected by a bracket which rests upon the sill. The bracket is comparatively massive and allows the tubes connecting the two units to pass through it. The units themselves are braced against the inner and outer sides of the wall.
A similar air conditioner is disclosed in U.S. Pat. No. 2,320,436. A low profile air conditioning unit is also described in U.S. Pat. No. 3,416,329 and still another unit of the general type straddling the windowsill can be found in U.S. Pat. No. 3,176,474. Mention may also be made of U.S. Pat. No. 5,253,485, 3,392,546, 3,296,820 and 3,448,590, all of which disclose split air conditioning units, namely units in which an outer housing contains the compressor, condenser coil and fan and the inner unit contains an air circulating blower. U.S. Pat. No. 3,554,496 deals with problems involved in the mounting of window air conditioners.
The prior art described above is characterized by the problem of having to mount a relatively heavy structure along the exterior of the building through the window opening. In other words, there is a significant problem with all of these earlier systems in mounting the heaviest portion of the air conditioner, namely, the outer unit, upon the exterior when access is available only through the window opening.